题目内容
巧算：
+
+
+
+
+
．
| 1 |
| 6 |
| 1 |
| 12 |
| 1 |
| 20 |
| 1 |
| 30 |
| 1 |
| 42 |
| 1 |
| 56 |
分析：把各个分数分别进行拆分，有规律地达到抵消的目的，依此计算即可．
解答：解：
+
+
+
+
+
，
=
-
+
-
+
-
+
-
+
-
+
-
，
=
-
，
=
．
| 1 |
| 6 |
| 1 |
| 12 |
| 1 |
| 20 |
| 1 |
| 30 |
| 1 |
| 42 |
| 1 |
| 56 |
=
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 6 |
| 1 |
| 6 |
| 1 |
| 7 |
| 1 |
| 7 |
| 1 |
| 8 |
=
| 1 |
| 2 |
| 1 |
| 8 |
=
| 3 |
| 8 |
点评：此题考查了分数的巧算，关键是对各个分数进行拆分，从而达到抵消的目的．
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